Heartnuts

Heartnut (Juglans ailantifolia var. cordiformis) is a type of walnut with a heart-shaped nut. All heartnuts are of the Japanese walnut species, or hybrids there of. The heartnut is a genetic “sport” or  mutation of the normal, wild type nut of Japanese walnut.

cracked shell and nutmeat of heartnut
Cracked heartnuts showing shell and meats.

Normal Japanese walnuts are cylindrical, elongated, rough or spiny, very thick-shelled and difficult to crack. In contrast, the heartnut is (more or less) Valentine-heart shaped and somewhat flattened. The heartnut is the easiest of all walnuts to husk and to crack. When moderate pressure is applied across the “shoulders” of the heart, the nut “pops” in two along the suture line, yielding two valentine-heart shaped halves. In cultivars with only “fair” to “good” cracking quality, the kernel breaks in half and comes out in two pieces. In the best cultivars, the kernel falls free from the shell in a single, unbroken piece – the only walnut in the world with this ability. On top of that, the heartnut is also the sweetest and mildest tasting of all the walnuts, beating out the so-called “English” walnut in taste tests every time. As if that weren’t enough, the heartnut has an incredible ability to store at room temperature.

 

Tom Wahl and Young heartnut
Tom Wahl standing by a 3 year old heartnut in Northern Arkansas.

The flavor actually develops in storage and peaks between five and eight years. Beyond 10 years at room temperature, heartnuts may become slightly stale, but not enough to keep them from being enjoyable.
The heartnut tree itself is incredibly fast growing. With adequate moisture and protection from weed competition they can put on six to eight feet of height growth per year in Iowa. The twigs are often as big around as broom handles. Leaves are compound and can be two to three feet long, with a very “tropical” look. Though the trees can become quite large, they tend to be low and spreading, like a live-oak. An old tree with a three foot diameter trunk and a 100 foot spread may be only 20 feet to 30 feet tall.
Heartnuts prefer moist, fertile, well-drained soil, though they will tolerate somewhat poorly drained soil better than most fruit and nut trees. They are best adapted to zones 5 and 6, with some of the hybrids suited through zone 4.
Superior heartnut cultivars can be grafted onto black walnut rootstock. The resulting tree can be twice as productive as seedling heartnuts or heartnuts grafted onto other heartnut rootstocks. Heartnuts are among the most challenging trees to graft, requiring great skill for success. For this reason, grafted heartnuts are very difficult to find in the nursery trade. More common are heartnut seedlings. The problem with seedlings is that they may grow into trees that bear nuts with no resemblance to those of their parents. Many heartnut seedlings “revert back to wild-type” – that is, their nuts will resemble the thick-shelled hard –to-crack wild Japanese walnuts. Some heartnut parent trees produce as much as 70% of offspring that grow into wild-type trees. On the other hand, the best heartnut parents will produce up to 90% heartnut offspring,

variations of heartnut shapes
Examples of various heartnuts from heartnut seedlings.

especially if they are pollenized by other good heartnut parents. If you are planting heartnut seedlings, you should plant about twice as many as the number of trees you want to end up with – that way, you can grow them up to bearing size, select the ones with the best nuts, and cull the poor ones.
Heartnuts are highly susceptible to walnut bunch disease. The disease is caused by a phytoplasma organism, and it’s transferred from tree to tree by leaf-hoppers. The disease causes “witches broom” type growth on the tree, and is frequently fatal. The good news is that the disease is apparently strongly linked to zinc deficiency in the soil. A foliar feed of the naturally occurring mineral zinc sulfate, applied in the spring, will usually clear up the disease in a single growing season. Zinc sulfate is applied to the soil around the drip line of the tree to prevent the disease from coming back.
Heartnuts have some great potential as a commercial tree. The unique shape of the nut alone makes them very attractive to consumers who eagerly pay $6 to $7 per pound for them. Add to this their rapid growth, heavy bearing, ease of husking and cracking, and great taste, and you have a tree that is well worth growing as a backyard tree or for a serious commercial venture. – Tom Wahl

Commercial Chestnut Growing Conference

Handouts from the Commercial Chestnut Growing Conference held on February 11, 2017 at Letts, Iowa

Iowa Chestnut Primer

Establishment of Chestnut Plantings with video of Tom Wahl’s talk.

Woodland_Suitability_Table

Mike Gold’s Chestnut Cultivar Handout and video of Mile Gold’s presentation.

All videos of the presentation are availabe at Red Fern Farm’s You Tube Channel

Details on the past conference:
Tom Wahl and Roger Smith are working together to provide a program on growing chestnuts commercially in the Midwest. It  will be held at the Letts Community Room in Letts, Iowa on February 11 from 9:30 am to 3:00 pm. Topics to be covered will include markets, cultural practices and economics. The outstanding potential for economic return of chestnuts will be stressed.

Chestnuts are a valuable nut crop that can be grown in a low-input, chemical free agroforestry system that includes permanent ground cover. Depending on soil types, they can be an excellent crop for land designated as highly erodible. Seedling chestnut trees of superior genetics can begin bearing nuts after 3 – 4 years on a good site and with good management. At 12 – 15 years they can produce 3,000 or more pounds per acre. In Iowa, chestnuts wholesale for an average of $2.60/pound.

The profit potential of chestnuts has encouraged the planting of chestnut groves throughout much of Iowa. Roger Smith, manager and owner of Prairie Grove Chestnut Growers, buys and sells chestnuts.  In 2016 he sorted, bagged and sold over 49,000 pounds of chestnuts grown in Iowa, Missouri and Illinois. He sees no end to the market potential of chestnuts and plans to plant an additional 25 acres of chestnut trees to his existing chestnut groves.

Speakers will include Roger Smith, Tom Wahl of Red Fern Farm, Drew Delang of the Natural Resource Conservation Service and Mike Gold of the Center for Agroforestry – University of Missouri. Preregistration is required. The registration of $20 includes lunch, snacks and a 26 page primer on growing Chestnuts in Iowa. Registration is available on line at Eventbee.com .  For more information or other registration options call Kathy Dice at 319/729-5905. This program is being sponsored by Practical Farmers of Iowa, Iowa State University Extension and Outreach, Louisa County, Red Fern Farm and Prairie Grove Chestnut Growers.